This should clear things up...
E-Cigarette Atomizer Types - eCig One
There are pictures of both 306 and 510 atomizers on that page.
Other than that, what Rickajho said.
I've never removed my bridge, because there simply doesn't seem to be any good reason to do so.
Not to say I haven't heard of reasons to do so, just that I don't think they are good reasons.
I use a 510 atomizer.
Many use a 306 atomizer.
You can get pros and cons for each.
But as far as I'm concerned, putting a drip tip on a 306 atomizer is a losing effort.